Electric continuous-flow heater with water deficiency safety device



Oct. 24, 1961 H. PUTZ 3,005,883

ELECTRIC CONTINUOUS-FLOW HEATER WITH WATER DEFICIENCY SAFETY DEVICE Filed Dec. 21, 1959 J44 J3 18 T 91 15 I 1 1 f; 6, 20 12 j 4 28 1 1 26 F lg. 2 i 5 IN V EN TOR.

United States Patent 3,005,888 ELECTRIC CONTINUOUS-FLOW HEATER WITH WATER DEFICIENCY SAFETY DEVICE Hans Piitz, Remscheid, Germany, assignor to Job. Vaillant K.G., Remscheid, Germany Filed Dec. 21, 1959, Ser. No. 861,033 Claims priority, application Germany Dec. 22, 1958 2 Claims. (Cl. 200-83) This invention is concerned with an electric continuous flow heater comprising a snap-action switch for switching on heating current, and in which the snap-action switch is actuated by means of a water deficiency safety device. As is well known with such continuous-flow heaters, a differential pressure is produced on a stagnation point upon the passage of the water, and which differential pressure acts as a stroke of a diaphragm switch. It is well known in the art that the switching on of an electric snap-action switch is effected by the stroke of a diaphragm switch. It is also well known per se with gas heated continuous-flow heaters not only that the gas valve may be opened by means of the diaphragm of such a diaphragm switch acting as a water deficiency safety device but also and at the same time that a water deficiency regulator may be controlled by means of this diaphragm. With electric continuous-flow heaters comprising a snapaction switch, however, this possibility cannot be realized without further difliculties because the diaphragm is, of course, loaded by the electric switch elements and there fore cannot perform a free control stroke.

On the other hand, the use of a water deficiency regulator is of great importance also with electric continuousflow heaters.

It is therefore the object of the present invention to make possible the use of a water deficiency regulator also with such diaphragm switches which are designed for the operation of an electric snap-action switch.

According to the invention this object is accomplished by having a tappet provided with two stop faces, and positively connecting the tappet with the diaphragm of the water deficiency safety device, and having the rocker of an electric tumbler switch so arranged between the stop faces of the tappet that the rocker, after having reached its switching-on position, is lifted off the stop face efiecting the switching operation so far that the diaphragm which simultaneously controls a water deficiency regulator is allowed freely to perform its control stroke.

Advantageously, the rocker moving between the stop faces of the tappet is connected at its free end with an extension spring which is attached with its other end to the fulcrum point of a bell crank lever system cooperating with a contact spring. With such an arrangement, the stop faces of the tappet cause the rocker, upon the movement of the diaphragm, to swing out in such a manner that each time it overcomes a dead center. The rocker, which is under the influence of the extension spring, then lifts off the stop face of the diaphragm switch tappet, so that the diaphragm is allowed to perform its control stroke freely without being loaded by the switch.

An embodiment of the invention is fully explained in the following detailed description and the drawing in which:

FIG. 1 is a cross section of the water regulator and switching apparatus in which the switch is shown in the open position.

FlG. 2 is a similar cross section in which the switch is shown in the closed position.

Cold water enters the water control unit -1 at 2. A diaphragm 3 subdivides thewater control unit 1 into two chambers 4 and 5.' The water supplied through the pipe 2 is controlled by the regulator 6, and dynamic 3,005,888 Patented Oct. 24., 1961 pressure builds up in the Venturi tube 7. This dynamic pressure produced in the Venturi tube becomes effective on the lower side of the diaphragm 3 in the chamber 5. The upper diaphragm chamber 4 is in communication with the low pressure side of the Venturi tube 7. The water flows from the Venturi tube 7 through the channel 8, the heat exchanger 9 and the pipe 10 to the hot water tap valve 11. Upon the stroke movement of the control pin 12 actuated by the diaphragm, this latter control pin 12 lifts the control stem or tappet 13. The short lever arm 16 of a double lever 17 moves in contact with the lower edge 14 of a recess 15 of the control stem 13. The fulcrum point of the lever is shown at 18. The long lever arm 17 supports on its free end 19 the end of a spring 20, which latter spring is rotatably 'mounted on this lever end. The other end 21 of this spring 20 is in like manner rotatably connected with two levers 22 and 23. Lever 23 is supported at the fulcrum point 18, while the lever 22 engages the electric contact lever 25 with its end 24.

Upon putting the water control unit 1 into operation, the control stem 13 moves upwards thereby overcoming the spring force of the springs 26 and 27.

The control stem or tappet has a recess 15 provided with a working face 14 and a working face 14', the working face 14 lying in contact with the lever end 16. Upon lifting of the control stem 13, the fulcrum point 19 of the spring 20 moves downwards and the other end of the spring 20 rests against the abutment 28. If now the lever 17 moves beyond the fulcrum point 21, spring 20 moves the fulcrum point 21 upwards while the other fulcrum point 19 now serves as a supporting point. As a consequence of this movement, lever 22 is pushed upwards so that the contact 29-29' is closed. The circuit is thus closed, so that the water is heated. During this changing over of the lever 17, its end 16 advances the control stem 113 in upward direction. Owing to this, there is a play produced between the lower edge of the lever 16 and the lower control edge 14 of the control stem. This play is so determined that, upon further upward movement of the control stem, the valve body 6 of the water flow regulator remaining in contact with the diaphragm 3 by action of a helical spring 30 moves on to its seating 6' into the regulating position. It is thereby achieved that the regulation of the water may be effected in well known manner without being affected or influenced by the switching means.

Invention is claimed as follows:

1. In an electric continuous-flow heater including a water flow regulator, a water deficiency safety device, a diaphragm responsive to water flow for controlling said regulator and said safety device, and a snap-action switch for switching on electric current, the improvement which comprises a tappet connected to said diaphragm having two spaced-apart stop faces, a pivotally mounted rocker arm connected at one end to said switch and having the other end arranged between said stop faces, said stop faces being so spaced that after said rocker arm has been moved to the switch-on position, the end of said rocker arm is maintained in a rest position spaced from each of said stop faces a suificient distance to permit movement of said diaphragm and normal operation of said water regulator.

2. In an electric continuous-flow heater including a water flow regulator, a water deficiency safety device, a diaphragm responsive to water flow for controlling said regulator and said safety device, and a snap-action switch for switching on electric current, the improvement which comprises a tappet connected to said diaphragm and having two-spaced apart stop faces, a pivotally mounted rocker arm having a first end thereof arranged between said stop faces, spring means having one end therof connected to a second end of said rocker arm, and a switch operating member connected at one end to said switch and at the other end to said spring means, the arrangement of said spring means being such that when the first end of said rocker arm is moved downwardly by said stop faces, said switch is opened, and when the first end of said rocker arm is raised by said stop faces said switch is closed and the first end of said rocker arm is snapped to a rest position spaced from each of said stop References Cited in the file of this patent UNITED STATES PATENTS Whitlock Ian. 13, 1914 Hunter Dec. 16, 1941 

